Skin diver fin



Aug. 30, 1966 J. MARKOWITZ SKIN DIVER FIN 2 Sheets-Sheet 1 Filed July 21, 1964 FIG. I

FIG. 2

FIG. 3

INVENTOR Joel Murkowitz 1966 J. MARKOWITZ 3,268,927

SKIN DIVER FIN Filed July 21, 1964 2 Sheets-sheet 2 I E n 23 Joel Murkowitz m on United States Patent 3,268,927 SKHN DIVER FIN Joel Markowitz, 239 Central Park W., New York, N.Y. Filed lady at, 1954, et. No. 384,144 6 Claims. (Cl. 9-304) This invention relates to a new and improved swimming aid. Particularly, the invention teaches a novel propulsion device which attaches to the leg of a swimmer or diver for greatly increasing his speed and mobility in the water.

With a few notable exceptions, men tend to view the sea as alien and dangerous; they have always thought of it, therefore, in a most under-confident, over-conservative manner. It is remarkable that the airplane was invented before the snorkle, and several years more were required for the development of the elementary flippers.

Flippers were a milestone in swimming and skin-diving. Not only did they greatly increase the speed, but far more important, they enormously increased mans capability in the water. He was able to dive more quickly and deeply, to rise more quickly to the surface, to rely completely on his le s for locomotion (leaving his hands free for other activities), to carry heavier equipment, to rise higher in the water during emergencies.

Though an important step forward, the flipper is actually an extremely faulty piece of equipment, doing its job very poorly in comparison to other skin-diving devices.

Most importantly, flippers are dependent upon and act against the small foot and angle muscles. These are very weak links in the chain of muscles providing locomotion, since they fatigue and cramp most easily, particularly when used in an unaccustomed manner. The powerful leg and thigh muscles must accommodate their activites to compensate for the limitations of these smaller muscles. Similarly, the design of the flippers, their size, weight and shape, are limited by their inadequate capacities.

A second defect of the flipper is its direction of action. Unlike the tails of fishes and seals, mans feet and therefore his flippers, point perpendicular to his body. In an attempt to improve this situation, the swimmer points his toes, but, besides increasing foot and leg fatigue by this unnatural posture, much of the force of the kick is still wasted, thrusting the feet upwards. Further postural compensation is necessary to counteract this, and while compensation is instinctive most of the large postural muscles are involved and further fatique results. These postural compensations are unnatural, muscles are used in an unaccustomed manner, they fatigue more rapidly than if they were used normally, and the swimmer moves awkwardly because of his inexperience with this unnatural posture. Meanwhile, only a relatively small component of the total force involved propels the swimmer directly forward.

And the downward-pointed flipper creates considerable drag, further increasing his inefiiciency.

Another disadvantage is that not even the relatively recent shoe-flippers fit as well as they should. They are of only a few sizes. While flippers with a back-strap are more reliable, they are also less comfortable, and the back-strap tends to slip. Since any flipper shifts constantly (i.e., with each foot movement or water current), friction on the skin is considerable, and feet are frequently rubbed badly. Considering the macerating effect of salt water to begin with, painful and raw lesions may severely limit the swimmer and skin diver.

Because flippers must be elastic they often fit poorly. This may allow one or both flippers to be torn from the feet and lost. This is particularly harrowing especially when contending with heavy currents and laden with 3,268,927 Patented August 30, 1966 heavy equipment. Flippers are lost even when the backstrap is tightened enough to almost impede circulation.

Another factor of importance; flippers are extremely awkward. It is impossible to climb up most boat ladders; one must remove and carry them, thus limiting the capacity and efficiency of ones hands. They are clumsy on land, easy to step on and trip over. One must lift ones feet high to walk in them. They are even more awkward in shallow water, causing enormous drag and stirring up sediment on the bottom. This clouding is disadvantageous in tropical waters where sea-urchins and sharp rocks, etc., must be seen to be avoided. Also, flippers seem to suck up mud and pebbles. It is most eflicient, therefore, to carry the flippers into the water until one can float, then jack-knife, and put on ones flippers in a cramped and uncomfortable posture. Should they contain or pick up pebbles or sand, they must be removed, shaken clean under water, and put on again. This is frequently inconvenient, but it must be done or the abrasive sand very quickly rubs raw spots in the skin.

It is extremely diflicult to work on the bottom standing with flippers. The ocean currents sway ones body, and as one tries to compensat any foot movement tends to throw one further off balance due to the further water resistance of the flippers.

In the prior art, attempts have been made to oifset one or more of the above disadvantages. Nevertheless, many of the disadvantages still remain.

In accordance with the instant invention, a swimming aid, herein referred to as a finned boot, is described, which overcomes the aforesaid problems. Briefly, the finned boot comprises: a sheathing or boot adapted to fit securely about the lower leg, a plurality of struts or arms afiixed at the upper end to said boot and extending parallel to the leg of the wearer and beyond the foot; and a fin supported at the lower end of said struts. When the wearer places the boot about the lower leg, the fin extends beyond the foot and lies on an extension of the longitudinal axis of the lower leg. The flat surface of the fin lies in substantially the same place as the body of the wearer, i.e., when a swimmer is in a prone position, the flat surface of the fin is in a plane parallel to the surface of the water.

While it is only necessary that the sheathing fit securely about the lower leg, i.e., from beneath the knee to above the ankle, several advantages are obtained by employing a boot wherein the foot as well as the lower leg is covered. A boot provides better support for the fin and lessens the possibility of restricting the circultaion of blood to and from the foot. Additionally, the boot is superior for walking on the bottom of the ocean or eliminates the need for separate foot gear.

In a particularly preferred embodiment of the invention, the upper and lower part of each strut are pivotally connected. This pivot permits the wearer to rotate the fin out of the swimming position to a walking position either in front of or behind the leg. This modification significantly enhances the versatility of the finned boot. Without it, of course, the fin would interfere with all walking and climbing functions. The finned boot employing the embodiment is also provided with means for locking the fin in and releasing the fin from the swimming position.

To further illustrate the invention, reference is made to the annexed figures.

FIGURE 1 illustrates a side view of the fin aflixed to the wearers legs while in the swimming position.

FIGURE 2 illustrates a top view of the fin while in the swimming position.

FIGURE 3 illustrates the orientation of the fin when not in use or in the walking position.

FIGURE 4 illustrates a front cross-section detailing the linkage between the upper and lower portion of the strut while the fin is in the swimming position.

FIGURE 5 illustrates a side view of the linkage while the fin is in the swimming position.

FIGURE 6 illustrates a side view of the linkage of the fin while in the walking position.

FIGURE 7 shows a side view of the modified fin in the walking position.

FIGURE 8 illustrates a front cross-section showing a modified locking means employing a slide bolt.

FIGURE 9 illustrates a cross-sectional view of the modified locking means.

Turning to FIGURE 1 the legs of the swimmer are surrounded by a sheathing or boot I which is secured to the leg by laces 2. These laces may be drawn as tightly as desired by the wearer so as to provide an immovable bond about the lower legs. Atfixed to the sheathing are the upper pair of struts 3. These struts are held in position by any convenient means such as the rivets 5. These rivets pass through the boot and maintain the strut 3, in fixed relationship to the boot 1. The lower end of the upper portion of the strut 3 is linked to the lower portion of the strut 6 at the pivot point 7. The upper and lower portions of the strut are maintained in the swimming position and walking position, respectively, by means which are more fully described in FIGURES 4 through 6. The lower part of the strut 6 is integrally united to the fin 8 by means of rivets 9.

The upper and lower portions of the struts 3 and 6 and the pivot point 7 are more clearly shown in FIG- URES 4, 5 and 6. FIGURES 4 and 5 show the position of the struts in the swimming position. It will be noted that they form an angle of 180 in respect to one another. The fixed relationship of the strut portion is maintained by means of detent pin 10 which passes through the aligned holes 11 and 12 in the lower and upper portions of the struts, respectively. This locking and locating mechanism should preferably be employed on both the lateral and medial strut of each pair. The pin 10 is maintained firmly seated in the aligned holes by means of tension springs 13. Hence, when the swimmer is propelling himself through the water with the fin in the position shown in FIGURE 1, the fin will maintain a fixed relationship to the lower leg.

In order to shift the fin into the walking position the wearer pulls out the pin 10 by means of knob 14 so as to disengage the hole 12. This will permit the lower portion of the strut and the fin afiixed thereto, to rotate about the pivot point 7. Each fin is rotated in turn to a position behind the lower leg as shown in FIGURE 3. The knob 14 serves as a convenient means for rotation. When moved to the appropriate acute angle the pin 10 actuated by the tension spring 13 engages the hole 15. This engagement maintains the upper and lower portion of the strut at an acute angle thereby permitting the swimmer to walk without impediment, climb a ladder, or go about his ordinary activities, without removing the entire unit.

FIGURE 7 illustrates an extended fin 8' particularly valuable for obtaining extra power for skin diving. Some convenience is lost in the walking position because of the length of the fin; however, this is secondary where additional power is needed.

FIGURES 8 and 9 show a modified locking means using a slide bolt. The slide bolt is slideably mounted in guides 21, the latter being united to the upper strut 3. When the lower strut 6 is moved into the swimming position slot 22 is positioned to receive slide bolt 20. Upon the insertion of the slide bolt 20 into the slot 22 as illustrated by the solid lines, the upper and lower struts are in fixed relationship. To release the locked strut, the slide bolt is moved rearwardly to the position indicated by the broken lines and numeral 20'. The rearward movement is limited by the stop 23. By disengaging the slide bolt 20, the lower strut may be revolved freely about the pivot point 7 to the walking position and held there by A any convenient means. This modification of the locking means is particularly advantageous since the bolt 20 serves to strengthen the rigidity of the entire strut.

Many modifications of the above figures are possible. For example, a torsional spring may be affixed to the upper and lower portions of the strut so that, when the pin 10 is disengaged from the hole 12, the spring will act to automatically bring the fin to the walking position. No further locking device is necessary since the tension of the spring is adequate to hold the fin 8 in position. Other spring devices and locking means will be apparent to those skilled in the art.

The contour of the fin may be any general shape known to those skilled in the art. Preferably, it should resemble the caudal fin of a fish, since, as it is well known, this is a highly efiicient shape for a sculling device.

It is particularly preferred that the fin should be longitudinally bowed to follow the contour of the calf of the leg. Alternatively, the fin, since it is flexible, may be strapped about the calf. This is advantageous since when the fin is in the walking position it offers little water resistance and does not encumber the wearer.

The area of the fin must be balanced against the increasing water resistance. It is desirable that the fin be as large as possible, but not so large as to severely retard the speed of the kick. Both the area and the rapidity of the kick determine the thrust developed. The inner edge of the fin is preferably straight, and particularly must not be curved inwardly, since, otherwise, the two fins will interfere with one another.

While it is preferable that the sheathing or boot be strapped to the leg by laces so as to provide a continuous grip about the leg along its full length, other devices may be used. For example, two or more straps may be suflicient to secure the upper portion of the strut about the leg. Rather than laces, belt and buckle arrangements, snaps, etc., may be used. For versatility of application, it is of course desirable that the sheathing resist the corrosiveness of salt water. Such materials include ligthweight plastics, synthetic rubber, and a variety of others known to those skilled in the art. A lining of foam rubber or other spongy material can be used to increase comfort, to better distribute pressure, and to prevent shifing.

The struts must be rigid members, though a slight degree of flexibility is preferable to brittleness. Various metals, hard rubbers, treated woods, and rigid plastics may be employed. The strut is secured to the fin and the boot by means of any conventional technique. Rivets and loops are examples of techniques which can be applied.

Similarly, a wide variety of materials may be used for constructing the fin. Hard rubbers and plastics as well as the more dense woods can be adaptable. Most desirably, the fin should be rigid at its upper portion and increase its flexibility towards the distal portion. This increased flexibility may be obtained merely by reducing the thickness of the distal portion.

Generally, the pivot point about which the fin rotates is located in the vicinity of the ankle. The rotating and locking mechanism are located closely thereto and are easily controlled by positioning the ankle within reach of the hand. By locating the pivot point higher on the leg, some added ease of control is obtained, but a shorter fin must be used. Conversely, lowering the pivot point lessens handling case, but permits the fin to be lengthened.

In another embodiment of the instant invention, the fin may be pre-molded in two sections. The sheathing may be molded of plastic integrally united with the upper portion of the strut. Reinforcing rods may be embedded in the strut for additional support. A smilar molding technique may be used to form the fin and the lower portion of the strut. The only additional step in such manufacture is to provide the necessary linkage. The buckles may also be preformed as an integral part of the sheathmg.

The instant invention provides a convenient technique can be readily shifted into the swimming position.

for enormously increasing the power and grace of the skin diver and swimmer. His capabilities in the water are greatly increased by the full utilization of the powerful muscles of his legs and thighs in the manner in which they are normally used. The gripping surface of the boot provides a uniform distribution of pressure along the leg without injury to the skin and prevents the possibility of loss in turbulent Water.

The boot may be placed on the leg on land, while in the walking position, until the swimmer enters the water from either the land or from a boat. When needed the flipper When leaving the water, or, if the diver desires to walk about the bottom of the ocean, he may readily re-position his flippers. It is unnecessay to remove the finned boot from the beginning to the end of the day. The fin is always accessible and no extra equipment need be carried about or remembered.

Various provisions may be adapted to make the flippers more useful to a skin diver. For example, a knife holder or other accessories may be attached to the sheathing. Other advantages of the invention as contrasted to the conventional flippers is the ability of the skin diver to wear rubber boots or use the flippers with or without a full rubber suit. This adaptability was never before possible.

In view of the foregoing disclosures, variations and modifications thereof will be apparent to one skilled in the art, and it is intended to include within the invention all such variations and modifications except as do not come within the scope of the appended claims.

What is claimed is:

1. An improved finned boot which comprises: a boot adapted to fit securely about the foot and lower leg; a first pair of struts longitudinally affixed to said boot; linking means for pivotally connecting said first pair of struts to one end of a second pair of struts in the vicinity of the ankle portion of said boots; a fin rigidly aflixed to the other end of said second pair of struts; lock-ing means to maintain said first and second pair of struts at an angle of substantially and means for rotating said second pair of struts to an acute angle in respect to said first pair of struts.

2. The finned boot of claim 1 wherein. said fin is contoured to the shape of the calf.

3. The finned boot of claim 1 wherein said locking means comprises a detent pin and a receiving hole.

4. A swimming device which comprises: a sheathing extending from between the ankle and the knee adapted to fit securely about the lower leg, struts aifixed at one end to said sheathing, and a fin aflixed at the other end and extending from below the bottom of the foot of the wearer substantially in line with the lower leg.

5. The swimming device of claim 4 wherein one end of said strut is pivotally connected to the other end.

6. The swimming device of claim 4 wherein said sheathing is part of a boot.

References Cited by the Examiner UNITED STATES PATENTS 805,525 11/1905 Bullock 9304 1,745,280 1/ 1930 Snapp 9-303 2,898,611 8/1959 Mooney 9-3 04 FOREIGN PATENTS 405,546 2/ 1934 Great Britain.

MILTON BUCHLER, Primary Examiner. ALFRED E. CORRIGAN, Examiner. 

1. AN IMPROVED FINNED BOOT WHICH COMPRISES: A BOOT ADAPTED TO FIT SECURELY ABOUT THE FOOT AND LOWER LEG; A FIRST PAIR OF STRUTS LONGITUDINALLY AFFIXED TO SAID BOOT; LINKING MEANS FOR PIVOTALLY CONNECTING AID FIRST PAIR OF STRUTS TO ONE END OF A SECOND PAIR OF STRUTS IN THE VICINITY OF THE ANKLE PORTION OF SAID BOOTS; A FIN RIGIDLY AFFIXED TO THE OTHER END OF SAID SECOND PAIR OF STRUTS; LOCKING MEANS TO MAINTAIN SAID FIRST AND SECOND PAIR OF STRUTS AS AN ANGLE OF SUBSTANTIALLY 180*; AND MEANS FOR ROTATING SAID SECOND PAIR OF STRUTS TO AN ACUTE ANGLE IN RESPECT TO SAID FIRST PAIR OF STRUTS. 